If any of those is set to C or POSIX, has a different encoding than
UTF-8 (sometimes spelled utf8) is empty (with the exception of
LC_ALL), or if you see any errors, you need to reconfigure your locale.

If your environment does not allow system-wide locale configuration (macOS,
shared server with generated but unconfigured locales), or if you want to
ensure it’s always configured independently of system settings.

To do this, you need to edit the configuration file for your shell. If you’re
using bash, it’s .bashrc (or .bash_profile on macOS). For zsh users,
.zshrc. Add this line (or equivalent in your shell):

exportLANG=en_US.UTF-8 LC_ALL=en_US.UTF-8

That should be enough. Note that those settings don’t apply to programs
not launched through a shell.

Python/Windows corner: Python 3.7 will fix this on Unix by assuming UTF-8
if it encounters the C locale. On Windows, Python 3.6 is using UTF-8
interactively, but not when using shell redirections to files or pipes.

This post was brought to you by ą — U+0105 LATIN SMALL LETTER A WITH OGONEK.

That’s all!

Hopefully, the guide worked for you and you can now use Unicode in many more places. If so, great! Otherwise, make sure you did everything as stated in this guide. If you are still stuck, ask for help in the comments.